US5233359A - Low difference pattern sidelobe pattern circuit - Google Patents
Low difference pattern sidelobe pattern circuit Download PDFInfo
- Publication number
- US5233359A US5233359A US07/864,985 US86498592A US5233359A US 5233359 A US5233359 A US 5233359A US 86498592 A US86498592 A US 86498592A US 5233359 A US5233359 A US 5233359A
- Authority
- US
- United States
- Prior art keywords
- coupler
- port
- phase
- array
- power
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
- H01Q25/02—Antennas or antenna systems providing at least two radiating patterns providing sum and difference patterns
Definitions
- This invention relates to a circuit configuration that, when implemented into an antenna power distribution network, provides independent sum and difference aperture excitations. This enables a reduction in the difference channel radiation pattern sidelobe levels with insignificant degradation on the sum channel radiation pattern.
- traveling wave there are two types of constrained feed networks for antenna array systems: traveling wave and corporate feeds. They are distinguished by the method by which they distribute RF energy.
- RF energy is inputted into a main transmission line and as it traverses the length of this line, small amounts are coupled off into the output ports of the feed. The path lengths from the input point to every feed output port are different.
- corporate feed the inputted RF energy is continuously divided into smaller amounts eventually reaching the output ports. In this case, the path lengths from the feed input point to every output port are identical.
- a travelling wave feed can be designed to have equal path lengths from the feed input point to each output port, but this approach adds hardware complexity.
- a monopulse antenna system which is characterized by reduced sidelobe levels in the difference mode.
- the system comprises an array of radiating elements disposed symmetrically about an array centerline.
- the system further includes a means operable only in the difference mode for driving the radiating elements located on one side of the centerline with signals which are out-of-phase with the signals driving the radiating elements located on the other side of the centerline.
- the system further includes a means for substantially reducing the amplitude of the signals driving a pair of radiating elements symmetrically located about the centerline.
- the invention is further characterized by a method for reducing sidelobe levels in the difference mode of a monopulse antenna system which includes an array of radiating elements disposed symmetrically about an array centerline.
- the method comprises the following steps:
- FIG. 1 is a schematic diagram of a conventional linear array of radiators, with a corporate power distribution network, fed by a monopulse network at its input.
- FIG. 2 is a schematic diagram of a linear array system employing the present invention.
- FIGS. 3 and 4 illustrate the hybrid divider circuit comprising the array system of FIG. 2, and the signal flow therethrough for the cases when the sum and difference ports of the array are excited respectively.
- FIG. 5 represents the computed difference pattern of a conventional 94 element linear array.
- FIGS. 6 and 7 present the impact on the difference pattern of an array as in FIG. 5, when the invention is employed to drive the RF levels at two elements symmetrically located about the center of the array to zero and to a quarter of the sum excitation, respectively.
- FIG. 1 shows a schematic circuit representation of an array system 20 comprising a conventional linear array of radiators 21-28.
- the array system has a corporate or parallel type of power distribution network comprising networks 30A and 30B, fed through a monopulse network 34 at the input.
- the monopulse network 34 consists of a magic T, and is characterized by a sum port 35 and a difference port 36.
- This step discontinuity, in the radiating element complex signal excitation (amplitude, phase), results in a difference far field radiation pattern with very high sidelobes.
- the resulting difference pattern has no clearly discernible sidelobe structure.
- a method to lower the difference channel sidelobes in accordance with the invention is to "smooth" out the step discontinuity in the complex signal excitation of the radiating aperture. This method is quite effective even when applied to as few as two radiating elements near the center of the array. It requires that the amplitude of pairs of elements, symmetrically located about the center of the array, be reduced considerably or even driven to zero.
- FIG. 2 An exemplary circuit configuration that provides reduced difference pattern sidelobes in accordance with the invention is presented in FIG. 2.
- the implementation shown involves only one pair of elements symmetrically located about the center of the array.
- the concept can be extended equally well to more pairs of elements.
- the array system 50 of FIG. 2 comprises a linear array of radiators 51-58, of which the radiator pair 54 and 55 are excited by a novel circuit 80 in accordance with the invention.
- the system 50 comprises a corporate feed comprising networks 70A and 70B whose inputs are fed by a monopulse circuit 76.
- the feed networks 70A and 70B and circuit 76 are identical to the feed networks 30A and 30B and circuit 34 of the system 20 of FIG. 1.
- the circuit 80 of FIG. 2 is shown in detail in FIG. 3 and comprises four, four-port microwave hybrid power dividers, e.g., magic T devices, Wilkinson power dividers, or other known types of four-port hybrid devices.
- the invention takes advantage of the directive properties of these four-port hybrid devices
- the four hybrids 90, 100, 110 and 120 are of identical power split design. Power from the networks 70A and 70B enters the circuit 80 at the respective input ports at input ports 81 and 82. In the sum mode, the RF energy at the ports 81 and 82 will be in phase; in the difference mode, the energy at these ports will be 180° out-of-phase.
- the power at port 81 enters the hybrid device 90, and is split into two signal components at ports 92 and 93.
- the signal components are in-phase and of amplitude C and D determined by the power split ratio of the hybrid 90.
- the power at port 82 enters the hybrid device 100, where it is split into two in-phase signal components at ports 102 and 10 of amplitude C and D.
- Port 92 of hybrid 90 is connected to port 112 of hybrid 110.
- Port 93 of hybrid 90 is connected to port 122 of hybrid 120.
- Port 102 of hybrid 100 is connected to port 113 of hybrid 110.
- Port 103 of hybrid 100 is connected to port 123 of hybrid 120.
- Hybrid 110 combines the signals at ports 112 and 113 into a sum signal at port 114 which drives the radiating element 54.
- hybrid 120 combines the signals at ports 122 and 123 into a sum signal at port 124 which drives radiating element 55.
- the power ratio provided by the design of the hybrids determines the power delivered to the radiating elements 54 and 55 and the amount of power that is delivered to and absorbed by the matched loads 91, 101, 111 and 121 connected to the isolated ports of the hybrid power dividers.
- equal power split results in no power into the radiating elements; all the power is delivered to the isolated port loads.
- high power split unbalance results in most of the power being delivered to the radiating elements 54 and 55 and the rest is directed to the hybrid loads.
- the circuit 80 operates along the following principles, with FIGS. 3 and 4 illustrating the signal flow through the circuit 80 when the sum and difference ports are excited, respectively.
- RF energy is fed into the sum port 77 of the monopulse circuit 76 of the array 50, identical RF circuit locations, with respect to the center of the array, anywhere along the array RF circuit are in phase relative to each other. Therefore, when RF energy reaches the hybrids 90, 100, 110 and 120 of circuit 80, and is initially divided and then recombined, there is no power loss into the isolated ports of the hybrids 90, 100, 110 and 120.
- the resulting amplitude and phase aperture distribution is not affected at all by the introduction of the circuit 80 between the feed network 70 and the array elements 54 and 55. It remains the same as provided by the feed networks 70A and 70B.
- the resulting amplitude excitation of the elements 54 and 55 connected to the circuit 80 is reduced or driven to zero.
- the resulting difference pattern has lower difference sidelobes without any effect on the sum pattern sidelobes.
- the introduction of the circuit 80 of this invention enables independent control of the sum and difference aperture excitations. Since reciprocity applies, the described circuit function is identical as the array operates on a receive mode.
- FIGS. 5, 6 and 7 present computed difference patterns of exemplary 94 element linear arrays.
- FIG. 5 shows the difference pattern of a conventional array.
- FIG. 6 presents the impact on the difference pattern when the invented circuit is introduced in the array feed. In this case two elements symmetrically located about the center of the array are driven to zero. It is apparent that there is a drop (improvement) in the average sidelobe level.
- FIG. 7 illustrates the impact on the difference pattern when the same two elements have their amplitudes reduced to a quarter of that of the sum excitation. Again, there is noticeable difference pattern sidelobe improvement.
Landscapes
- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
Description
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/864,985 US5233359A (en) | 1992-04-07 | 1992-04-07 | Low difference pattern sidelobe pattern circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/864,985 US5233359A (en) | 1992-04-07 | 1992-04-07 | Low difference pattern sidelobe pattern circuit |
Publications (1)
Publication Number | Publication Date |
---|---|
US5233359A true US5233359A (en) | 1993-08-03 |
Family
ID=25344469
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US07/864,985 Expired - Lifetime US5233359A (en) | 1992-04-07 | 1992-04-07 | Low difference pattern sidelobe pattern circuit |
Country Status (1)
Country | Link |
---|---|
US (1) | US5233359A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080068266A1 (en) * | 2005-11-23 | 2008-03-20 | Northrop Grumman Corporation | Beamforming for spatial sidelobe cancellation and AMR direction finding |
US9484978B2 (en) | 2015-03-25 | 2016-11-01 | Htc Corporation | System and method for communication with adjustable signal phase and power |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3803624A (en) * | 1972-09-01 | 1974-04-09 | Gen Electric | Monopulse radar antenna array feed network |
-
1992
- 1992-04-07 US US07/864,985 patent/US5233359A/en not_active Expired - Lifetime
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3803624A (en) * | 1972-09-01 | 1974-04-09 | Gen Electric | Monopulse radar antenna array feed network |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080068266A1 (en) * | 2005-11-23 | 2008-03-20 | Northrop Grumman Corporation | Beamforming for spatial sidelobe cancellation and AMR direction finding |
US9484978B2 (en) | 2015-03-25 | 2016-11-01 | Htc Corporation | System and method for communication with adjustable signal phase and power |
TWI587646B (en) * | 2015-03-25 | 2017-06-11 | 宏達國際電子股份有限公司 | System and method for communication |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4849763A (en) | Low sidelobe phased array antenna using identical solid state modules | |
US5349364A (en) | Electromagnetic power distribution system comprising distinct type couplers | |
US4652880A (en) | Antenna feed network | |
US7400215B2 (en) | Method and apparatus for increasing performance in a waveguide-based spatial power combiner | |
US4825172A (en) | Equal power amplifier system for active phase array antenna and method of arranging same | |
US5012254A (en) | Plural level beam-forming netowrk | |
US4814775A (en) | Reconfigurable beam-forming network that provides in-phase power to each region | |
US4924234A (en) | Plural level beam-forming network | |
US3518695A (en) | Antenna array multifrequency and beam steering control multiplex feed | |
US10033083B1 (en) | Ka-band waveguide hybrid divider with unequal and arbitrary power output ratio | |
US4905011A (en) | Concentric ring antenna | |
US4503434A (en) | Lossless arbitrary output dual mode network | |
US2789271A (en) | Hybrid ring coupling arrangement | |
US5717405A (en) | Four-port phase and amplitude equalizer for feed enhancement of wideband antenna arrays with low sum and difference sidelobes | |
US4223283A (en) | Two into three port phase shifting power divider | |
US4731614A (en) | Phased array scanning system | |
US5233359A (en) | Low difference pattern sidelobe pattern circuit | |
GB1600346A (en) | Antenna system having modular coupling network | |
US5270671A (en) | Negative slope phase skewer | |
US3525995A (en) | Amplitude tapering,nonsymmetrical binary feed networks for highpower hf phased arrays | |
US4499471A (en) | Reconfigurable dual mode network | |
US20040235528A1 (en) | Overlapped subarray antenna feed network for wireless communication system phased array antenna | |
JP3345767B2 (en) | Multi-beam antenna feed circuit | |
US4743911A (en) | Constant beamwidth antenna | |
US5291155A (en) | Microwave buffer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HUGHES AIRCRAFT COMPANY A CORPORATION OF DELAWA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:PANARETOS, STEVE K.;REEL/FRAME:006081/0804 Effective date: 19920406 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
AS | Assignment |
Owner name: HE HOLDINGS, INC., A DELAWARE CORP., CALIFORNIA Free format text: CHANGE OF NAME;ASSIGNOR:HUGHES AIRCRAFT COMPANY, A CORPORATION OF THE STATE OF DELAWARE;REEL/FRAME:016087/0541 Effective date: 19971217 Owner name: RAYTHEON COMPANY, MASSACHUSETTS Free format text: MERGER;ASSIGNOR:HE HOLDINGS, INC. DBA HUGHES ELECTRONICS;REEL/FRAME:016116/0506 Effective date: 19971217 |
|
FPAY | Fee payment |
Year of fee payment: 12 |
|
AS | Assignment |
Owner name: OL SECURITY LIMITED LIABILITY COMPANY, DELAWARE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:RAYTHEON COMPANY;REEL/FRAME:029215/0160 Effective date: 20120730 |